It's possible to complete the MXL2001 Royer Mod for $35 if you had to

[777funk]

I am always setting out to do things cheap if I can. For me half of the fun of DIY is to make it affordable and it all adds up if you do enough projects. So this was no exception. I ended up spending around $100 plus the used mic after you figure the Jensen DB/E cased transformer in. But I could have done it for around $35 if I had to. Here's how:

-Enclosure (free - see photos)
-Power Transformer - 30VA Hammond 24-0-24VAC for $12
-Canare  mic cable 15' $15
-Perfboard, resistors, caps (had in the bins) but assume $3 worth
-Reuse stock MXL transformer
-5840 Tube $3 if bought in bulk (I purchased 4) on ebay
-Cut up an old mic cable
-Cut up an old computer power cable (bought a box of them years ago)
-1A solder lead (made for PCBs) fuse in line with the hot mains wire going to the transformer
-Heat shrink
-NO jacks as you can see in the pic

I sat and thought about enclosures and wasn't coming up with much then I thought, why not use old tin cans. They're steel and will shield noise, they're rigid enough, they're easy to work with... and... it worked great. I drilled 3/8" holes and used a grommet/bushing for the shielded cable to pass through and a press fit power cord grommet for the power. Then I cut 4 slits in the inner can about half way down and pressed the second can onto the first. It's solid and it's quiet.

All said and done, I used the Jensen DB/E cased and put it in the power supply housing. Worked very well and sounds very good. The only changes I made to Royer's circuit were to swap the 5840 to a 6205, used the cased version of the Jensen inside the power supply (only because it was available), and put a 10k feedback resistor from the output side of the 1uF cap back to the cathode of the tube. This seemed better to my ears (a little smoother high freq and of course slight gain reduction).

 

[liquidify]

Awesome.

 

[shabtek]

and scary

edit: not so much the dc as much as the mains rolling around...cheepness is not so at the cost of safety.

 

[bruce0]

The stock transformer is like 2:1 I think.  The jensen db/e is 12:1.  So maybe find some old mic transformer to run backwards (I have used a Beyer 10:1 in the LDC royermod successfully. A 4:1 created a way too hot mic signal.)


Also... It would sound better if you used italian tomato cans instead of domestic.

Hmmmm. 105V DC rolling around on the floor in a tin can.  Yikes!

 

[ricardo]

Also... It would sound better if you used italian tomato cans instead of domestic.

Now, now, Bruce!  That's Golden Pinnae talk.

It will suffice if the tomatoes are grown by virgins in Unobtainium mulch.